34. HOMOTROPIC ALLOSTERIC ACTIVATION

Question 1

1. What is Homotropic Allosteric Regulation?

Answer 1

• it is the binding of a substrate to an active site of one subunit
• it locks all the subunits into active conformation

Question 2

2. What is Co-operativity?

Answer 2

• this is a special form of positive allosteric regulation
  (activation)
• it amplifies enzyme activity

Question 3

3. What is an example of Co-operativity?

Answer 3

• O2 binding to haemoglobin
• O2 is the allosteric activator
• haemoglobin is a protein

Question 4

4. What does the bonding of substrate at one subunit increase?

Answer 4

• the binding affinity of the other subunits
• oxygen is an allosteric activator

Question 5

5. What does an Allosteric Activator do?

Answer 5

• it is the substrate
• it locks all the subunits into a active conformation

Question 6

6. What is a Heterotropic Allosteric Modulator?

Answer 6

• it is a non-competitive inhibitor and activator

Question 7

7. Is a regulatory molecule the enzyme’s substrate?

Answer 7

• NO

Question 8

8. What is AMP?

Answer 8

• this is Adenosine Monophosphate
• it is a Heterotropic Allosteric Activator of PFK
• PFK = Phoshphofructokinase
  = this is a glycolysis enzyme

Question 9

9. What is CO2?

Answer 9

• a Heterotropic Allosteric Inhibitor
• it is a non-competitive inhibitor of haemoglobin
• it reduces the Haemoglobin’s affinity for oxygen
• oxygen is then released into the tissue

Question 10

10. What is a Homotropic Allosteric Modulator?

Answer 10

• it is a competitive inhibitor and an activator
• it is both a substrate for its target enzyme
  AND a regulatory molecule of the enzyme’s activity
• it is typically an activator of the enzyme

Question 11

11. Which Homotropic Allosteric Modulators are not activators of the enzyme?

Answer 11

• CO for Haemoglobin

Question 12

12. What is O2?

Answer 12

• it is a Homotropic Allosteric Activator of Haemoglobin

Question 13

13. What is CO?

Answer 13

• a competitive inhibitor
• it binds to haemoglobin at the same site as the oxygen
• it has a higher affinity for Haemoglobin than Oxygen
  does
• it does not allow for oxygen to be released into the
  tissue
• this can cause poisoning

Question 14

14. Where are enzymes that are participating in the same pathway located?

Answer 14

• close to each other

Question 15

15. How can Cellular Enzymes be structured?

Answer 15

• they can be grouped into complexes
• they can be incorporated into membranes
• they can be contained inside organelles

Question 16

16. Does this Flow Diagram make sense?

Answer 16

• yes

Question 17

17. Does this summary make sense?

Answer 17

• yes

Question 18

18. Answer this question.

Answer 18

• D